1. Field of the Invention
The present invention relates to an electronic data management system, an electronic data management apparatus, electronic data management methods, programs for causing a computer to execute the methods, and computer-readable storage media storing the programs.
2. Description of the Related Art
In recent years, awareness of the importance of safe management of electronic data including documents and images has been raised with increasing information security consciousness. In particular, to prevent important electronic data content from being illegally altered, there has been proposed a management system in which electronic data is attached with attribute information indicating that the data is the “original” (hereinafter referred to as the “original attribute”) in order to manage the original data separately from other electronic data (see, for example, Japanese Laid-open Patent Publication No. 2000-285024). Electronic data sets, each attached with the original attribute, are managed under a management policy that prevents data from being edited in content and erased.
There is also known a technique in which feature information such as a hash value is extracted from electronic data managed as the original and compared with a predetermined characteristic amount. In accordance with a result of the comparison, it is guaranteed that the content of electronic data managed as the original has not illegally be altered and it is verified that the electronic data managed is the original.
Electronic data can be re-created by duplicating electronic data attached with the original attribute. In that case, the duplicate data is attached with attribute information indicating that the data is a “duplicate” (hereinafter referred to as the “duplicate attribute”), in order to manage the duplicate data by a management method different from that for the original data. In general, the duplicate is created for backup of the original, or for the purpose of eliminating the necessity for an unspecified user to directly access the original, and soon. Electronic data sets, each attached with the duplicate attribute, are managed under a management policy that permits the duplicate data to be erased but prohibits the creation of a further duplicate based on the duplicate data, which is different from the management policy for the original.
Furthermore, electronic data attached with the original attribute can be transferred via a network from a transfer source server to a transfer destination server. In that case, attribute information having been attached to the electronic data before data transfer can also be transferred together with the electronic data. Moreover, transfer history information indicating that the electronic data has been transferred can be added to attribute information of the electronic data after data transfer.
With this prior art, the attribute information indicating the transfer history can be managed only on the transfer destination side, although electronic data attached with the original attribute can be transferred from the transfer source side to the transfer destination side, posing a problem that the transfer destination of the original electronic data becomes unknown on the transfer source side. Since the electronic data is simply transferred from the transfer source side to the transfer destination side, nothing is left on the transfer source side. As a result, a user on the transfer source side who wishes to access the electronic data does not know the data transfer destination and even the fact that the electronic data has already been transferred from the transfer source side. This can cause confusion on the data transfer source side, in particular, in organizations where people and/or electronic data are frequently transferred, such as schools, companies in which numerous personal data are managed, and hospitals in which electronic medical charts are managed.